Construction work is shown in June 2013, at the Grand Ethiopian Renaissance Dam, near Assosa in the Benishangul-Gumuz region of Ethiopia, near Sudan. The dam will have the capacity to produce 6,000 megawatts of electricity and become the biggest hydroelectric power station in Africa.

The greatest public works project in Africa will reach a critical stage this year. The Grand Ethiopian Renaissance Dam, on the Blue Nile, is more than halfway complete. This year, the first diversions of flow of the Blue Nile will begin.

Eventually, the Blue Nile will be stopped sufficiently to fill up the reservoir behind the dam.

This diversion of water, though small this year, has already become a flashpoint in the politics of Africa. If the diversion issue is handled correctly, however, the dam will propel Ethiopia from the ranks of underdeveloped countries through the kind of rural electrification America experienced in the 1920s.

The Nile has two components: the White Nile, which starts in Lake Victoria, bordering Uganda, Kenya, and Tanzania, and the Blue Nile, which starts in Ethiopia, winding from Lake Tana through gorges, descending in altitude until it flows into Sudan.

The White Nile meets the Blue Nile in Khartoum, Sudan, from which it proceeds north to the Egyptian border. After entering Egypt, the Nile encounters the Aswan High Dam, creating an expansive reservoir, Lake Nassar. That reservoir permits regulation of the release of water to irrigate farmland alongside the course of the Nile throughout Egypt, ending the annual floods that had overflowed the Nile’s banks for thousands of years.

The dam is the realization of the most profound national aspiration of Ethiopia. It was never an international project. The World Bank refused to fund it, because Egypt insists on no diminution of the water it receives from the Nile; and the U.S., Egypt’s friend, exercises a veto at the World Bank.

So the Ethiopians taxed themselves, solicited loans from more than half of their population voluntarily tithing every year and obtained help from the Chinese. It is now a symbol of Ethiopia’s move into the ranks of the developed world; national pride is running high as its completion nears.

In equal measure, national pride and sensitivity runs high in Egypt. Egypt and Sudan claim 100 percent of the right to the waters of the Nile, based on historic use, and a 1959 treaty co-authored by those countries and Britain, which was purportedly acting on behalf of its soon-to-be former colonies: Uganda, Kenya, and Tanganikya (today’s Tanzania). Britain had liberated Ethiopia from Mussolini’s Italy in World War II, and stayed in administrative control of major parts of the Ethiopian government for ten years thereafter. Britain’s disregard for Ethiopia’s interest in declaring that Ethiopia would be prevented from diverting Nile water reflected those lingering colonial attitudes, much resented in Ethiopia.

So, Egypt’s resistance to the dam is a mirror to Ethiopia’s enthusiasm for the dam. Egypt’s position reminds Ethiopians of Britain’s colonial disdain. Tensions are made even higher by a worrisome rise in religious tension. Egypt, especially under the short-lived rule of Mohamed Morsi, emphasized that 2/3 of Ethiopians are Christian, in contrast with Muslim Egypt. Egypt’s current leader, Abdel Fattah el-Sisi, overthrew Morsi and banned his Muslim Brotherhood-affiliated political party, but the Christian-Muslim contrast is ever present and available for political exploitation.

Traditionally, Sudan has sided with Egypt in regard to anything touching the Nile. The 1959 agreement gave 5/6 of the water to Egypt, 1/6 to Sudan. That was more than Sudan was capable of using at its then level of development. The Ethiopian dam changes Sudan’s interests in two important respects. First, unlike Aswan, this dam is upstream from Sudan; meaning it can be used to control the flow of water into Sudan that today overflows the banks of the Blue Nile during the flood time; creating a more steady and reliable flow conducive to greater agricultural production in Sudan. Second, the dam will produce more electricity than Ethiopia can use, with Sudan as the likely purchaser of the excess. Sudan is coming around to the Ethiopian side of the dam issue; and this works strongly against any Egyptian effort to revive the Morsi-era language that the dam is a Christian construct to hurt Muslim nations.

To avoid an international crisis, Egypt also must be brought around. The key is that the dam is for hydropower, not for irrigation, as its location at the lowest elevation in Ethiopia demonstrates. Once its reservoir is filled, therefore, water flow will resume undiminished to Egypt. Gradual filling of the reservoir, and coordination with Egypt’s Lake Nasser water releases, can mitigate even this temporary effect on Egypt. Ethiopia should give that assurance in a binding commitment, and a potential crisis can be turned into a blessing for millions.

Tom Campbell is a professor at the Fowler School of Law and the Argyros School of Business and Economics at Chapman University. As a Member of Congress, he served on the Africa Subcommittee of the House International Relations Committee. These views are his own.